In next generation cloud communication technology, wireless network architecture includes a large group of Antenna Ports (ATPs) which are connected to a central processor (or a Remote Base Station (RBS)) and carries out baseband processing for the entire network.
Availability of baseband signals corresponding to all the User Equipment (UEs) in the network provides multiple benefits including simplified user scheduling, automatic load balancing and the like. As the density of the ATPs grow, transmit power of the Base Station (BS) can be reduced to low values without compromising the network performance. In conventional networks, such high density deployment may lead to frequent handovers.
In conventional systems, the base station (BS) may employ spatial multiplexing (SM) techniques using multiple antennas in downlink. Similarly, the cloud radio may be designed to handle multi-stream transmission from each TP. FIG. 1 is a high level architecture of a Cloud Radio Access Network (CRAN). In a cloud radio, the network may assign the base station identification (BS ID) number to a group of antenna ports while individual antenna ports may be given a unique antenna port number. FIG. 2 illustrates a conventional Heterogeneous networks (HetNets) Cloud Radio with a plurality of macro cells and pico cells illustrating a HetNet Cloud Radio. Third Generation Partnership (3GPP) standard introduced HetNets in Release-10 of the 4G Long-Term-Evolution (LTE) standard. This feature allows deployment of small cells (Pico cells and Femto cells). All cells can fully utilize an entire available bandwidth in universal frequency reuse-one mode. The introduction of Pico cells within the coverage area of a Macro cell may lead to mutual interference between the Macro and Pico cells.
Existing CSI feedback methods do not distinguish between BS of its own cluster and the neighboring cluster. To mitigate intra-cluster interference ones needs CSI of BSs/ATPs that belong to the same cluster. However, since the RBS uses centralized precoding to eliminate intra-cluster interference, there is no need to obtain CSI of BSs/ATPs that belong to neighboring clusters. The inter-cluster scheduling can be used to mitigate inter-cluster interference if the UE feedback the IDs of BS that are present in the neighboring clusters but can cause dominant interference to the UE.